压缩文件的应用

  从网上搜到的一个例子，主要是讲将多个文件压缩的问题。
注意区分ZipOutputStream， GZIPOutputStream，JarOutputStream的区别。
例子是将硬盘上的文件压缩，也可将内存中的字符串进行压缩，只需要换成ByteArrayInputStream就可以了。

package zip;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.Adler32;
import java.util.zip.CheckedInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

public class ZipUtils {

private static final int BUFFER = 8192;

private static void log(String msg) {
System.out.println(msg);
}

private static String getFileName(String filePath) {
int index = filePath.indexOf(".");
return filePath.substring(0, index);
}


public static void zip(String sourceFilePath) {
File fileDir = new File(sourceFilePath);
if (fileDir.exists()) {
log(fileDir.getPath() + " Starting Zip ...");
long startTime = System.currentTimeMillis();
doZip(fileDir);
long endTime = System.currentTimeMillis();
long costTime = endTime - startTime;
log("Zip Success!");
log("use time -- " + costTime + " millsec!");
} else {
log("can't find the File!");
}
}

public static void unZip(String zipFilePath) {
File fileDir = new File(zipFilePath);
if (fileDir.exists()) {
log(fileDir.getPath() + " Starting UnZip ...");
long startTime = System.currentTimeMillis();
doUnZip(fileDir);
long endTime = System.currentTimeMillis();
long costTime = endTime - startTime;
log("UnZip Success!");
log("use time -- " + costTime + " millsec!");
} else {
log("can't find the File!");
}
}

public static void doZip(File file) {
List<File> fileList = new ArrayList<File>();
List<File> allFiles = (ArrayList<File>) searchFiles(file.getPath(),
fileList);

Object[] fileArray = allFiles.toArray();

BufferedInputStream in = null;
FileInputStream fis = null;
ZipOutputStream zos = null;
FileOutputStream fos = null;
try {
fos = new FileOutputStream(file.getParent() + File.separator
+ file.getName() + ".zip");
zos = new ZipOutputStream(new BufferedOutputStream(fos, BUFFER));

zos.setLevel(9);

byte[] data = new byte[BUFFER];

for (int i = 0; i < fileArray.length; i++) {
// 设置压缩文件入口entry,为被读取的文件创建压缩条目
File tempFile = new File(fileArray[i].toString());
String rootStr = file.getPath();
String entryStr = null;
// entry以相对路径的形式设置。以文件夹C:\temp例如temp\test.doc或者test.xls
// 如果设置不当，会出现拒绝访问等错误
// 分别处理单个文件/目录的entry
if (rootStr.equals(tempFile.getPath())) {
entryStr = tempFile.getName();
} else {
entryStr = tempFile.getPath().substring(
(rootStr + File.separator).length());
}
log(entryStr);

ZipEntry entry = new ZipEntry(entryStr);
zos.putNextEntry(entry);

fis = new FileInputStream(tempFile);
in = new BufferedInputStream(fis, BUFFER);

int count;
while ((count = in.read(data, 0, BUFFER)) != -1) {
zos.write(data, 0, count);
}
}

} catch (Exception ex) {
ex.printStackTrace();
} finally {
try {
if (in != null) {
in.close();
}
if (zos != null) {
zos.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

public static void doUnZip(File file) {
try {
final int BUFFER = 2048;
BufferedOutputStream dest = null;
FileInputStream fis = new FileInputStream(file);
CheckedInputStream checksum = new CheckedInputStream(fis,
new Adler32());
ZipInputStream zis = new ZipInputStream(new BufferedInputStream(
checksum));
ZipEntry entry;
while ((entry = zis.getNextEntry()) != null) {
log("Extracting: " + entry);
int count;
byte[] data = new byte[BUFFER];
log("unzip to " + getFileName(file.getPath()));

FileOutputStream fos = new FileOutputStream(getFileName(file
.getPath())
+ File.separator + newDir(file, entry.getName()));

dest = new BufferedOutputStream(fos, BUFFER);
while ((count = zis.read(data, 0, BUFFER)) != -1) {
dest.write(data, 0, count);
}
dest.flush();
dest.close();
}
zis.close();
System.out
.println("Checksum: " + checksum.getChecksum().getValue());
} catch (Exception e) {
e.printStackTrace();
}
}

public static List<File> searchFiles(String sourceFilePath,
List<File> fileList) {
File fileDir = new File(sourceFilePath);
if (fileDir.isDirectory()) {
File[] subfiles = fileDir.listFiles();
for (int i = 0; i < subfiles.length; i++) {
searchFiles(subfiles[i].getPath(), fileList);
}
} else {
fileList.add(fileDir);
}

return fileList;
}

@SuppressWarnings("static-access")
private static String newDir(File file, String entryName) {

String rootDir = getFileName(file.getPath());
log("root：" + rootDir);
int index = entryName.lastIndexOf("\\");
String dirStr = new File(rootDir).getParent();
log(dirStr);
if (index != -1) {

String path = entryName.substring(0, index);
log("new Dir：" + rootDir + file.separator + path);
new File(rootDir + file.separator + path).mkdirs();

log("entry:" + entryName.substring(0, index));
} else {
new File(rootDir).mkdirs();
log("entry:" + entryName);
}
return entryName;

}

}